“Today, unelected judges cast aside the will of the people of California who voted to protect traditional marriage,” Romney said in a statement. “This decision does not end this fight, and I expect it to go to the Supreme Court.

“That prospect underscores the vital importance of this election and the movement to preserve our values. I believe marriage is between a man and a woman and, as president, I will protect traditional marriage and appoint judges who interpret the Constitution as it is written and not according to their own politics and prejudices,” Romney said.

Gingrich said the ruling meant that “more and more Americans are being exposed to the radical overreach of federal judges and their continued assault on the Judeo-Christian foundations of the United States."

“Should the Supreme Court fail to heed the disastrous lessons of its own history and attempt to impose its will on the marriage debate in this country by affirming today’s Ninth Circuit decision, it will bear the burden of igniting a constitutional crisis of the first order,” Gingrich said.

In a tweet, Santorum said that the 7 million Californians who voted for Proposition 8 “had their rights stripped away today by activist 9th Circuit judges. As president I will work to protect marriage.”

"For a court, any court, to usurp the power and will of the people in this manner on an issue this fundamental to the foundation of our society is wrong," Santorum said in a subsequent statement.

In Washington, President Obama's reaction to the Proposition 8 decision was much like the president's stance on gay marriage -- somewhat unclear.

White House press secretary Jay Carney said the White House wouldn't be commenting on the court's rejection of California's same-sex marriage ban, saying that the administration doesn't weigh in on ongoing litigation.

But the president's top spokesman also seemed to suggest an endorsement of the decision, without saying so.

"He has long opposed divisive and discriminatory efforts to deny rights and benefits to same-sex couples," Carney said.